// Emacs style mode select	 -*- C++ -*-
//-----------------------------------------------------------------------------
//
// $Id:$
//
// Copyright (C) 1993-1996 by id Software, Inc.
//
// This source is available for distribution and/or modification
// only under the terms of the DOOM Source Code License as
// published by id Software. All rights reserved.
//
// The source is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// FITNESS FOR A PARTICULAR PURPOSE. See the DOOM Source Code License
// for more details.
//
// $Log:$
//
// DESCRIPTION:
//		Movement, collision handling.
//		Shooting and aiming.
//
//-----------------------------------------------------------------------------

static const char
rcsid[] = "$Id: p_map.c,v 1.5 1997/02/03 22:45:11 b1 Exp $";

#include <stdlib.h>
#include "m_bbox.h"
#include "m_random.h"
#include "i_system.h"

#include "doomdef.h"
#include "p_local.h"

#include "s_sound.h"

// State.
#include "doomstat.h"
#include "r_state.h"
// Data.
#include "sounds.h"


fixed_t			tmbbox[4];
mobj_t*			tmthing;
int				tmflags;
fixed_t			tmx;
fixed_t			tmy;


// If "floatok" true, move would be ok
// if within "tmfloorz - tmceilingz".
boolean			floatok;

fixed_t			tmfloorz;
fixed_t			tmceilingz;
fixed_t			tmdropoffz;

// keep track of the line that lowers the ceiling,
// so missiles don't explode against sky hack walls
line_t*			ceilingline;

// keep track of special lines as they are hit,
// but don't process them until the move is proven valid
#define MAXSPECIALCROSS			8

line_t*			spechit[MAXSPECIALCROSS];
int				numspechit;



//
// TELEPORT MOVE
//

//
// PIT_StompThing
//
boolean PIT_StompThing (mobj_t* thing)
{
    fixed_t		blockdist;

    if (!(thing->flags & MF_SHOOTABLE) )
        return true;

    blockdist = thing->radius + tmthing->radius;

    if ( abs(thing->x - tmx) >= blockdist
            || abs(thing->y - tmy) >= blockdist )
    {
        // didn't hit it
        return true;
    }

    // don't clip against self
    if (thing == tmthing)
        return true;

    // monsters don't stomp things except on boss level
    if ( !tmthing->player && gamemap != 30)
        return false;

    P_DamageMobj (thing, tmthing, tmthing, 10000);

    return true;
}


//
// P_TeleportMove
//
boolean
P_TeleportMove
( mobj_t*		thing,
  fixed_t		x,
  fixed_t		y )
{
    int					xl;
    int					xh;
    int					yl;
    int					yh;
    int					bx;
    int					by;

    subsector_t*		newsubsec;

    // kill anything occupying the position
    tmthing = thing;
    tmflags = thing->flags;

    tmx = x;
    tmy = y;

    tmbbox[BOXTOP] = y + tmthing->radius;
    tmbbox[BOXBOTTOM] = y - tmthing->radius;
    tmbbox[BOXRIGHT] = x + tmthing->radius;
    tmbbox[BOXLEFT] = x - tmthing->radius;

    newsubsec = R_PointInSubsector (x,y);
    ceilingline = NULL;

    // The base floor/ceiling is from the subsector
    // that contains the point.
    // Any contacted lines the step closer together
    // will adjust them.
    tmfloorz = tmdropoffz = newsubsec->sector->floorheight;
    tmceilingz = newsubsec->sector->ceilingheight;

    validcount++;
    numspechit = 0;

    // stomp on any things contacted
    xl = (tmbbox[BOXLEFT] - bmaporgx - MAXRADIUS)>>MAPBLOCKSHIFT;
    xh = (tmbbox[BOXRIGHT] - bmaporgx + MAXRADIUS)>>MAPBLOCKSHIFT;
    yl = (tmbbox[BOXBOTTOM] - bmaporgy - MAXRADIUS)>>MAPBLOCKSHIFT;
    yh = (tmbbox[BOXTOP] - bmaporgy + MAXRADIUS)>>MAPBLOCKSHIFT;

    for (bx=xl ; bx<=xh ; bx++)
        for (by=yl ; by<=yh ; by++)
            if (!P_BlockThingsIterator(bx,by,PIT_StompThing))
                return false;

    // the move is ok,
    // so link the thing into its new position
    P_UnsetThingPosition (thing);

    thing->floorz = tmfloorz;
    thing->ceilingz = tmceilingz;
    thing->x = x;
    thing->y = y;

    P_SetThingPosition (thing);

    return true;
}


//
// MOVEMENT ITERATOR FUNCTIONS
//


//
// PIT_CheckLine
// Adjusts tmfloorz and tmceilingz as lines are contacted
//
boolean PIT_CheckLine (line_t* ld)
{
    if (tmbbox[BOXRIGHT] <= ld->bbox[BOXLEFT]
            || tmbbox[BOXLEFT] >= ld->bbox[BOXRIGHT]
            || tmbbox[BOXTOP] <= ld->bbox[BOXBOTTOM]
            || tmbbox[BOXBOTTOM] >= ld->bbox[BOXTOP] )
        return true;

    if (P_BoxOnLineSide (tmbbox, ld) != -1)
        return true;

    // A line has been hit

    // The moving thing's destination position will cross
    // the given line.
    // If this should not be allowed, return false.
    // If the line is special, keep track of it
    // to process later if the move is proven ok.
    // NOTE: specials are NOT sorted by order,
    // so two special lines that are only 8 pixels apart
    // could be crossed in either order.

    if (!ld->backsector)
        return false;			// one sided line

    if (!(tmthing->flags & MF_MISSILE) )
    {
        if ( ld->flags & ML_BLOCKING )
            return false;		// explicitly blocking everything

        if ( !tmthing->player && ld->flags & ML_BLOCKMONSTERS )
            return false;		// block monsters only
    }

    // set openrange, opentop, openbottom
    P_LineOpening (ld);

    // adjust floor / ceiling heights
    if (opentop < tmceilingz)
    {
        tmceilingz = opentop;
        ceilingline = ld;
    }

    if (openbottom > tmfloorz)
        tmfloorz = openbottom;

    if (lowfloor < tmdropoffz)
        tmdropoffz = lowfloor;

    // if contacted a special line, add it to the list
    if (ld->special)
    {
        spechit[numspechit] = ld;
        numspechit++;
    }

    return true;
}

//
// PIT_CheckThing
//
boolean PIT_CheckThing (mobj_t* thing)
{
    fixed_t				blockdist;
    boolean				solid;
    int					damage;

    if (!(thing->flags & (MF_SOLID|MF_SPECIAL|MF_SHOOTABLE) ))
        return true;

    blockdist = thing->radius + tmthing->radius;

    if ( abs(thing->x - tmx) >= blockdist
            || abs(thing->y - tmy) >= blockdist )
    {
        // didn't hit it
        return true;
    }

    // don't clip against self
    if (thing == tmthing)
        return true;

    // check for skulls slamming into things
    if (tmthing->flags & MF_SKULLFLY)
    {
        damage = ((P_Random()%8)+1)*tmthing->info->damage;

        P_DamageMobj (thing, tmthing, tmthing, damage);

        tmthing->flags &= ~MF_SKULLFLY;
        tmthing->momx = tmthing->momy = tmthing->momz = 0;

        P_SetMobjState (tmthing, tmthing->info->spawnstate);

        return false;			// stop moving
    }


    // missiles can hit other things
    if (tmthing->flags & MF_MISSILE)
    {
        // see if it went over / under
        if (tmthing->z > thing->z + thing->height)
            return true;				// overhead
        if (tmthing->z+tmthing->height < thing->z)
            return true;				// underneath

        if (tmthing->target && (
                    tmthing->target->type == thing->type ||
                    (tmthing->target->type == MT_KNIGHT && thing->type == MT_BRUISER)||
                    (tmthing->target->type == MT_BRUISER && thing->type == MT_KNIGHT) ) )
        {
            // Don't hit same species as originator.
            if (thing == tmthing->target)
                return true;

            if (thing->type != MT_PLAYER)
            {
                // Explode, but do no damage.
                // Let players missile other players.
                return false;
            }
        }

        if (! (thing->flags & MF_SHOOTABLE) )
        {
            // didn't do any damage
            return !(thing->flags & MF_SOLID);
        }

        // damage / explode
        damage = ((P_Random()%8)+1)*tmthing->info->damage;
        P_DamageMobj (thing, tmthing, tmthing->target, damage);

        // don't traverse any more
        return false;
    }

    // check for special pickup
    if (thing->flags & MF_SPECIAL)
    {
        solid = thing->flags&MF_SOLID;
        if (tmflags&MF_PICKUP)
        {
            // can remove thing
            P_TouchSpecialThing (thing, tmthing);
        }
        return !solid;
    }

    return !(thing->flags & MF_SOLID);
}


//
// MOVEMENT CLIPPING
//

//
// P_CheckPosition
// This is purely informative, nothing is modified
// (except things picked up).
//
// in:
//	a mobj_t (can be valid or invalid)
//	a position to be checked
//	 (doesn't need to be related to the mobj_t->x,y)
//
// during:
//	special things are touched if MF_PICKUP
//	early out on solid lines?
//
// out:
//	newsubsec
//	floorz
//	ceilingz
//	tmdropoffz
//	 the lowest point contacted
//	 (monsters won't move to a dropoff)
//	speciallines[]
//	numspeciallines
//
boolean
P_CheckPosition
( mobj_t*		thing,
  fixed_t		x,
  fixed_t		y )
{
    int					xl;
    int					xh;
    int					yl;
    int					yh;
    int					bx;
    int					by;
    subsector_t*		newsubsec;

    tmthing = thing;
    tmflags = thing->flags;

    tmx = x;
    tmy = y;

    tmbbox[BOXTOP] = y + tmthing->radius;
    tmbbox[BOXBOTTOM] = y - tmthing->radius;
    tmbbox[BOXRIGHT] = x + tmthing->radius;
    tmbbox[BOXLEFT] = x - tmthing->radius;

    newsubsec = R_PointInSubsector (x,y);
    ceilingline = NULL;

    // The base floor / ceiling is from the subsector
    // that contains the point.
    // Any contacted lines the step closer together
    // will adjust them.
    tmfloorz = tmdropoffz = newsubsec->sector->floorheight;
    tmceilingz = newsubsec->sector->ceilingheight;

    validcount++;
    numspechit = 0;

    if ( tmflags & MF_NOCLIP )
        return true;

    // Check things first, possibly picking things up.
    // The bounding box is extended by MAXRADIUS
    // because mobj_ts are grouped into mapblocks
    // based on their origin point, and can overlap
    // into adjacent blocks by up to MAXRADIUS units.
    xl = (tmbbox[BOXLEFT] - bmaporgx - MAXRADIUS)>>MAPBLOCKSHIFT;
    xh = (tmbbox[BOXRIGHT] - bmaporgx + MAXRADIUS)>>MAPBLOCKSHIFT;
    yl = (tmbbox[BOXBOTTOM] - bmaporgy - MAXRADIUS)>>MAPBLOCKSHIFT;
    yh = (tmbbox[BOXTOP] - bmaporgy + MAXRADIUS)>>MAPBLOCKSHIFT;

    for (bx=xl ; bx<=xh ; bx++)
        for (by=yl ; by<=yh ; by++)
            if (!P_BlockThingsIterator(bx,by,PIT_CheckThing))
                return false;

    // check lines
    xl = (tmbbox[BOXLEFT] - bmaporgx)>>MAPBLOCKSHIFT;
    xh = (tmbbox[BOXRIGHT] - bmaporgx)>>MAPBLOCKSHIFT;
    yl = (tmbbox[BOXBOTTOM] - bmaporgy)>>MAPBLOCKSHIFT;
    yh = (tmbbox[BOXTOP] - bmaporgy)>>MAPBLOCKSHIFT;

    for (bx=xl ; bx<=xh ; bx++)
        for (by=yl ; by<=yh ; by++)
            if (!P_BlockLinesIterator (bx,by,PIT_CheckLine))
                return false;

    return true;
}


//
// P_TryMove
// Attempt to move to a new position,
// crossing special lines unless MF_TELEPORT is set.
//
boolean
P_TryMove
( mobj_t*		thing,
  fixed_t		x,
  fixed_t		y )
{
    fixed_t		oldx;
    fixed_t		oldy;
    int			side;
    int			oldside;
    line_t*		ld;

    floatok = false;
    if (!P_CheckPosition (thing, x, y))
        return false;			// solid wall or thing

    if ( !(thing->flags & MF_NOCLIP) )
    {
        if (tmceilingz - tmfloorz < thing->height)
            return false;		// doesn't fit

        floatok = true;

        if ( !(thing->flags&MF_TELEPORT)
                &&tmceilingz - thing->z < thing->height)
            return false;		// mobj must lower itself to fit

        if ( !(thing->flags&MF_TELEPORT)
                && tmfloorz - thing->z > 24*FRACUNIT )
            return false;		// too big a step up

        if ( !(thing->flags&(MF_DROPOFF|MF_FLOAT))
                && tmfloorz - tmdropoffz > 24*FRACUNIT )
            return false;		// don't stand over a dropoff
    }

    // the move is ok,
    // so link the thing into its new position
    P_UnsetThingPosition (thing);

    oldx = thing->x;
    oldy = thing->y;
    thing->floorz = tmfloorz;
    thing->ceilingz = tmceilingz;
    thing->x = x;
    thing->y = y;

    P_SetThingPosition (thing);

    // if any special lines were hit, do the effect
    if (! (thing->flags&(MF_TELEPORT|MF_NOCLIP)) )
    {
        while (numspechit--)
        {
            // see if the line was crossed
            ld = spechit[numspechit];
            side = P_PointOnLineSide (thing->x, thing->y, ld);
            oldside = P_PointOnLineSide (oldx, oldy, ld);
            if (side != oldside)
            {
                if (ld->special)
                    P_CrossSpecialLine (ld-lines, oldside, thing);
            }
        }
    }

    return true;
}


//
// P_ThingHeightClip
// Takes a valid thing and adjusts the thing->floorz,
// thing->ceilingz, and possibly thing->z.
// This is called for all nearby monsters
// whenever a sector changes height.
// If the thing doesn't fit,
// the z will be set to the lowest value
// and false will be returned.
//
boolean P_ThingHeightClip (mobj_t* thing)
{
    boolean				onfloor;

    onfloor = (thing->z == thing->floorz);

    P_CheckPosition (thing, thing->x, thing->y);
    // what about stranding a monster partially off an edge?

    thing->floorz = tmfloorz;
    thing->ceilingz = tmceilingz;

    if (onfloor)
    {
        // walking monsters rise and fall with the floor
        thing->z = thing->floorz;
    }
    else
    {
        // don't adjust a floating monster unless forced to
        if (thing->z+thing->height > thing->ceilingz)
            thing->z = thing->ceilingz - thing->height;
    }

    if (thing->ceilingz - thing->floorz < thing->height)
        return false;

    return true;
}



//
// SLIDE MOVE
// Allows the player to slide along any angled walls.
//
fixed_t			bestslidefrac;
fixed_t			secondslidefrac;

line_t*			bestslideline;
line_t*			secondslideline;

mobj_t*			slidemo;

fixed_t			tmxmove;
fixed_t			tmymove;



//
// P_HitSlideLine
// Adjusts the xmove / ymove
// so that the next move will slide along the wall.
//
void P_HitSlideLine (line_t* ld)
{
    int					side;

    angle_t				lineangle;
    angle_t				moveangle;
    angle_t				deltaangle;

    fixed_t				movelen;
    fixed_t				newlen;


    if (ld->slopetype == ST_HORIZONTAL)
    {
        tmymove = 0;
        return;
    }

    if (ld->slopetype == ST_VERTICAL)
    {
        tmxmove = 0;
        return;
    }

    side = P_PointOnLineSide (slidemo->x, slidemo->y, ld);

    lineangle = R_PointToAngle2 (0,0, ld->dx, ld->dy);

    if (side == 1)
        lineangle += ANG180;

    moveangle = R_PointToAngle2 (0,0, tmxmove, tmymove);
    deltaangle = moveangle-lineangle;

    if (deltaangle > ANG180)
        deltaangle += ANG180;
    //	I_Error ("SlideLine: ang>ANG180");

    lineangle >>= ANGLETOFINESHIFT;
    deltaangle >>= ANGLETOFINESHIFT;

    movelen = P_AproxDistance (tmxmove, tmymove);
    newlen = FixedMul (movelen, finecosine[deltaangle]);

    tmxmove = FixedMul (newlen, finecosine[lineangle]);
    tmymove = FixedMul (newlen, finesine[lineangle]);
}


//
// PTR_SlideTraverse
//
boolean PTR_SlideTraverse (intercept_t* in)
{
    line_t*		li;

    if (!in->isaline)
        I_Error ("PTR_SlideTraverse: not a line?");

    li = in->d.line;

    if ( ! (li->flags & ML_TWOSIDED) )
    {
        if (P_PointOnLineSide (slidemo->x, slidemo->y, li))
        {
            // don't hit the back side
            return true;
        }
        goto isblocking;
    }

    // set openrange, opentop, openbottom
    P_LineOpening (li);

    if (openrange < slidemo->height)
        goto isblocking;				// doesn't fit

    if (opentop - slidemo->z < slidemo->height)
        goto isblocking;				// mobj is too high

    if (openbottom - slidemo->z > 24*FRACUNIT )
        goto isblocking;				// too big a step up

    // this line doesn't block movement
    return true;

    // the line does block movement,
    // see if it is closer than best so far
isblocking:
    if (in->frac < bestslidefrac)
    {
        secondslidefrac = bestslidefrac;
        secondslideline = bestslideline;
        bestslidefrac = in->frac;
        bestslideline = li;
    }

    return false;		// stop
}



//
// P_SlideMove
// The momx / momy move is bad, so try to slide
// along a wall.
// Find the first line hit, move flush to it,
// and slide along it
//
// This is a kludgy mess.
//
void P_SlideMove (mobj_t* mo)
{
    fixed_t				leadx;
    fixed_t				leady;
    fixed_t				trailx;
    fixed_t				traily;
    fixed_t				newx;
    fixed_t				newy;
    int					hitcount;

    slidemo = mo;
    hitcount = 0;

retry:
    if (++hitcount == 3)
        goto stairstep;			// don't loop forever


    // trace along the three leading corners
    if (mo->momx > 0)
    {
        leadx = mo->x + mo->radius;
        trailx = mo->x - mo->radius;
    }
    else
    {
        leadx = mo->x - mo->radius;
        trailx = mo->x + mo->radius;
    }

    if (mo->momy > 0)
    {
        leady = mo->y + mo->radius;
        traily = mo->y - mo->radius;
    }
    else
    {
        leady = mo->y - mo->radius;
        traily = mo->y + mo->radius;
    }

    bestslidefrac = FRACUNIT+1;

    P_PathTraverse ( leadx, leady, leadx+mo->momx, leady+mo->momy,
                     PT_ADDLINES, PTR_SlideTraverse );
    P_PathTraverse ( trailx, leady, trailx+mo->momx, leady+mo->momy,
                     PT_ADDLINES, PTR_SlideTraverse );
    P_PathTraverse ( leadx, traily, leadx+mo->momx, traily+mo->momy,
                     PT_ADDLINES, PTR_SlideTraverse );

    // move up to the wall
    if (bestslidefrac == FRACUNIT+1)
    {
        // the move most have hit the middle, so stairstep
stairstep:
        if (!P_TryMove (mo, mo->x, mo->y + mo->momy))
            P_TryMove (mo, mo->x + mo->momx, mo->y);
        return;
    }

    // fudge a bit to make sure it doesn't hit
    bestslidefrac -= 0x800;
    if (bestslidefrac > 0)
    {
        newx = FixedMul (mo->momx, bestslidefrac);
        newy = FixedMul (mo->momy, bestslidefrac);

        if (!P_TryMove (mo, mo->x+newx, mo->y+newy))
            goto stairstep;
    }

    // Now continue along the wall.
    // First calculate remainder.
    bestslidefrac = FRACUNIT-(bestslidefrac+0x800);

    if (bestslidefrac > FRACUNIT)
        bestslidefrac = FRACUNIT;

    if (bestslidefrac <= 0)
        return;

    tmxmove = FixedMul (mo->momx, bestslidefrac);
    tmymove = FixedMul (mo->momy, bestslidefrac);

    P_HitSlideLine (bestslideline);		// clip the moves

    mo->momx = tmxmove;
    mo->momy = tmymove;

    if (!P_TryMove (mo, mo->x+tmxmove, mo->y+tmymove))
    {
        goto retry;
    }
}


//
// P_LineAttack
//
mobj_t*			linetarget;		// who got hit (or NULL)
mobj_t*			shootthing;

// Height if not aiming up or down
// ???: use slope for monsters?
fixed_t			shootz;

int				la_damage;
fixed_t			attackrange;

fixed_t			aimslope;

// slopes to top and bottom of target
extern fixed_t	topslope;
extern fixed_t	bottomslope;


//
// PTR_AimTraverse
// Sets linetaget and aimslope when a target is aimed at.
//
boolean
PTR_AimTraverse (intercept_t* in)
{
    line_t*				li;
    mobj_t*				th;
    fixed_t				slope;
    fixed_t				thingtopslope;
    fixed_t				thingbottomslope;
    fixed_t				dist;

    if (in->isaline)
    {
        li = in->d.line;

        if ( !(li->flags & ML_TWOSIDED) )
            return false;				// stop

        // Crosses a two sided line.
        // A two sided line will restrict
        // the possible target ranges.
        P_LineOpening (li);

        if (openbottom >= opentop)
            return false;				// stop

        dist = FixedMul (attackrange, in->frac);

        if (li->frontsector->floorheight != li->backsector->floorheight)
        {
            slope = FixedDiv (openbottom - shootz , dist);
            if (slope > bottomslope)
                bottomslope = slope;
        }

        if (li->frontsector->ceilingheight != li->backsector->ceilingheight)
        {
            slope = FixedDiv (opentop - shootz , dist);
            if (slope < topslope)
                topslope = slope;
        }

        if (topslope <= bottomslope)
            return false;				// stop

        return true;					// shot continues
    }

    // shoot a thing
    th = in->d.thing;
    if (th == shootthing)
        return true;					// can't shoot self

    if (!(th->flags&MF_SHOOTABLE))
        return true;					// corpse or something

    // check angles to see if the thing can be aimed at
    dist = FixedMul (attackrange, in->frac);
    thingtopslope = FixedDiv (th->z+th->height - shootz , dist);

    if (thingtopslope < bottomslope)
        return true;					// shot over the thing

    thingbottomslope = FixedDiv (th->z - shootz, dist);

    if (thingbottomslope > topslope)
        return true;					// shot under the thing

    // this thing can be hit!
    if (thingtopslope > topslope)
        thingtopslope = topslope;

    if (thingbottomslope < bottomslope)
        thingbottomslope = bottomslope;

    aimslope = (thingtopslope+thingbottomslope)/2;
    linetarget = th;

    return false;						// don't go any farther
}


//
// PTR_ShootTraverse
//
boolean PTR_ShootTraverse (intercept_t* in)
{
    fixed_t				x;
    fixed_t				y;
    fixed_t				z;
    fixed_t				frac;

    line_t*				li;

    mobj_t*				th;

    fixed_t				slope;
    fixed_t				dist;
    fixed_t				thingtopslope;
    fixed_t				thingbottomslope;

    if (in->isaline)
    {
        li = in->d.line;

        if (li->special)
            P_ShootSpecialLine (shootthing, li);

        if ( !(li->flags & ML_TWOSIDED) )
            goto hitline;

        // crosses a two sided line
        P_LineOpening (li);

        dist = FixedMul (attackrange, in->frac);

        if (li->frontsector->floorheight != li->backsector->floorheight)
        {
            slope = FixedDiv (openbottom - shootz , dist);
            if (slope > aimslope)
                goto hitline;
        }

        if (li->frontsector->ceilingheight != li->backsector->ceilingheight)
        {
            slope = FixedDiv (opentop - shootz , dist);
            if (slope < aimslope)
                goto hitline;
        }

        // shot continues
        return true;


        // hit line
hitline:
        // position a bit closer
        frac = in->frac - FixedDiv (4*FRACUNIT,attackrange);
        x = trace.x + FixedMul (trace.dx, frac);
        y = trace.y + FixedMul (trace.dy, frac);
        z = shootz + FixedMul (aimslope, FixedMul(frac, attackrange));

        if (li->frontsector->ceilingpic == skyflatnum)
        {
            // don't shoot the sky!
            if (z > li->frontsector->ceilingheight)
                return false;

            // it's a sky hack wall
            if	(li->backsector && li->backsector->ceilingpic == skyflatnum)
                return false;
        }

        // Spawn bullet puffs.
        P_SpawnPuff (x,y,z);

        // don't go any farther
        return false;
    }

    // shoot a thing
    th = in->d.thing;
    if (th == shootthing)
        return true;			// can't shoot self

    if (!(th->flags&MF_SHOOTABLE))
        return true;			// corpse or something

    // check angles to see if the thing can be aimed at
    dist = FixedMul (attackrange, in->frac);
    thingtopslope = FixedDiv (th->z+th->height - shootz , dist);

    if (thingtopslope < aimslope)
        return true;			// shot over the thing

    thingbottomslope = FixedDiv (th->z - shootz, dist);

    if (thingbottomslope > aimslope)
        return true;			// shot under the thing


    // hit thing
    // position a bit closer
    frac = in->frac - FixedDiv (10*FRACUNIT,attackrange);

    x = trace.x + FixedMul (trace.dx, frac);
    y = trace.y + FixedMul (trace.dy, frac);
    z = shootz + FixedMul (aimslope, FixedMul(frac, attackrange));

    // Spawn bullet puffs or blod spots,
    // depending on target type.
    if (in->d.thing->flags & MF_NOBLOOD)
        P_SpawnPuff (x,y,z);
    else
        P_SpawnBlood (x,y,z, la_damage);

    if (la_damage)
        P_DamageMobj (th, shootthing, shootthing, la_damage);

    // don't go any farther
    return false;

}


//
// P_AimLineAttack
//
fixed_t
P_AimLineAttack
( mobj_t*		t1,
  angle_t		angle,
  fixed_t		distance )
{
    fixed_t		x2;
    fixed_t		y2;

    angle >>= ANGLETOFINESHIFT;
    shootthing = t1;

    x2 = t1->x + (distance>>FRACBITS)*finecosine[angle];
    y2 = t1->y + (distance>>FRACBITS)*finesine[angle];
    shootz = t1->z + (t1->height>>1) + 8*FRACUNIT;

    // can't shoot outside view angles
    topslope = 100*FRACUNIT/160;
    bottomslope = -100*FRACUNIT/160;

    attackrange = distance;
    linetarget = NULL;

    P_PathTraverse ( t1->x, t1->y,
                     x2, y2,
                     PT_ADDLINES|PT_ADDTHINGS,
                     PTR_AimTraverse );

    if (linetarget)
        return aimslope;

    return 0;
}


//
// P_LineAttack
// If damage == 0, it is just a test trace
// that will leave linetarget set.
//
void
P_LineAttack
( mobj_t*		t1,
  angle_t		angle,
  fixed_t		distance,
  fixed_t		slope,
  int			damage )
{
    fixed_t		x2;
    fixed_t		y2;

    angle >>= ANGLETOFINESHIFT;
    shootthing = t1;
    la_damage = damage;
    x2 = t1->x + (distance>>FRACBITS)*finecosine[angle];
    y2 = t1->y + (distance>>FRACBITS)*finesine[angle];
    shootz = t1->z + (t1->height>>1) + 8*FRACUNIT;
    attackrange = distance;
    aimslope = slope;

    P_PathTraverse ( t1->x, t1->y,
                     x2, y2,
                     PT_ADDLINES|PT_ADDTHINGS,
                     PTR_ShootTraverse );
}



//
// USE LINES
//
mobj_t*			usething;

boolean PTR_UseTraverse (intercept_t* in)
{
    int			side;

    if (!in->d.line->special)
    {
        P_LineOpening (in->d.line);
        if (openrange <= 0)
        {
            S_StartSound (usething, sfx_noway);

            // can't use through a wall
            return false;
        }
        // not a special line, but keep checking
        return true ;
    }

    side = 0;
    if (P_PointOnLineSide (usething->x, usething->y, in->d.line) == 1)
        side = 1;

    //	return false;			// don't use back side

    P_UseSpecialLine (usething, in->d.line, side);

    // can't use for than one special line in a row
    return false;
}


//
// P_UseLines
// Looks for special lines in front of the player to activate.
//
void P_UseLines (player_t*		player)
{
    int			angle;
    fixed_t		x1;
    fixed_t		y1;
    fixed_t		x2;
    fixed_t		y2;

    usething = player->mo;

    angle = player->mo->angle >> ANGLETOFINESHIFT;

    x1 = player->mo->x;
    y1 = player->mo->y;
    x2 = x1 + (USERANGE>>FRACBITS)*finecosine[angle];
    y2 = y1 + (USERANGE>>FRACBITS)*finesine[angle];

    P_PathTraverse ( x1, y1, x2, y2, PT_ADDLINES, PTR_UseTraverse );
}


//
// RADIUS ATTACK
//
mobj_t*			bombsource;
mobj_t*			bombspot;
int				bombdamage;


//
// PIT_RadiusAttack
// "bombsource" is the creature
// that caused the explosion at "bombspot".
//
boolean PIT_RadiusAttack (mobj_t* thing)
{
    fixed_t		dx;
    fixed_t		dy;
    fixed_t		dist;

    if (!(thing->flags & MF_SHOOTABLE) )
        return true;

    // Boss spider and cyborg
    // take no damage from concussion.
    if (thing->type == MT_CYBORG
            || thing->type == MT_SPIDER)
        return true;

    dx = abs(thing->x - bombspot->x);
    dy = abs(thing->y - bombspot->y);

    dist = dx>dy ? dx : dy;
    dist = (dist - thing->radius) >> FRACBITS;

    if (dist < 0)
        dist = 0;

    if (dist >= bombdamage)
        return true;	// out of range

    if ( P_CheckSight (thing, bombspot) )
    {
        // must be in direct path
        P_DamageMobj (thing, bombspot, bombsource, bombdamage - dist);
    }

    return true;
}


//
// P_RadiusAttack
// Source is the creature that caused the explosion at spot.
//
void
P_RadiusAttack
( mobj_t*		spot,
  mobj_t*		source,
  int			damage )
{
    int			x;
    int			y;

    int			xl;
    int			xh;
    int			yl;
    int			yh;

    fixed_t		dist;

    dist = (damage+MAXRADIUS)<<FRACBITS;
    yh = (spot->y + dist - bmaporgy)>>MAPBLOCKSHIFT;
    yl = (spot->y - dist - bmaporgy)>>MAPBLOCKSHIFT;
    xh = (spot->x + dist - bmaporgx)>>MAPBLOCKSHIFT;
    xl = (spot->x - dist - bmaporgx)>>MAPBLOCKSHIFT;
    bombspot = spot;
    bombsource = source;
    bombdamage = damage;

    for (y=yl ; y<=yh ; y++)
        for (x=xl ; x<=xh ; x++)
            P_BlockThingsIterator (x, y, PIT_RadiusAttack );
}



//
// SECTOR HEIGHT CHANGING
// After modifying a sectors floor or ceiling height,
// call this routine to adjust the positions
// of all things that touch the sector.
//
// If anything doesn't fit anymore, true will be returned.
// If crunch is true, they will take damage
//	as they are being crushed.
// If Crunch is false, you should set the sector height back
//	the way it was and call P_ChangeSector again
//	to undo the changes.
//
boolean			crushchange;
boolean			nofit;


//
// PIT_ChangeSector
//
boolean PIT_ChangeSector (mobj_t*		thing)
{
    mobj_t*		mo;

    if (P_ThingHeightClip (thing))
    {
        // keep checking
        return true;
    }


    // crunch bodies to giblets
    if (thing->health <= 0)
    {
        P_SetMobjState (thing, S_GIBS);

        thing->flags &= ~MF_SOLID;
        thing->height = 0;
        thing->radius = 0;

        // keep checking
        return true;
    }

    // crunch dropped items
    if (thing->flags & MF_DROPPED)
    {
        P_RemoveMobj (thing);

        // keep checking
        return true;
    }

    if (! (thing->flags & MF_SHOOTABLE) )
    {
        // assume it is bloody gibs or something
        return true;
    }

    nofit = true;

    if (crushchange && !(leveltime&3) )
    {
        P_DamageMobj(thing,NULL,NULL,10);

        // spray blood in a random direction
        mo = P_SpawnMobj (thing->x,
                          thing->y,
                          thing->z + thing->height/2, MT_BLOOD);

        mo->momx = (P_Random() - P_Random ())<<12;
        mo->momy = (P_Random() - P_Random ())<<12;
    }

    // keep checking (crush other things)
    return true;
}



//
// P_ChangeSector
//
boolean
P_ChangeSector
( sector_t*		sector,
  boolean		crunch )
{
    int			x;
    int			y;

    nofit = false;
    crushchange = crunch;

    // re-check heights for all things near the moving sector
    for (x=sector->blockbox[BOXLEFT] ; x<= sector->blockbox[BOXRIGHT] ; x++)
        for (y=sector->blockbox[BOXBOTTOM]; y<= sector->blockbox[BOXTOP] ; y++)
            P_BlockThingsIterator (x, y, PIT_ChangeSector);


    return nofit;
}

